Before you jump into Scala I'd recommend being familiar with Java and (at the least) being comfortable with the basics of an ML-like language or Haskell. Having had experience with a scripting language like Ruby or Python helps too.
Knowing Java, Haskell, Ruby, and Python already, I found it really easy to jump into Scala with the references listed on the Scala site. If you do have experience with Java/statically-typed FP (or if you're just feeling brave) that's where I'd recommend looking.
